There are a number of NATO airfields on each map. Airfields are generally very strongly guarded by NATO, usually with a large number of infantry as well as static gun emplacements and vehicles ranging from Hunters to Cheetahs.
Airfields are an important asset for the resistance. They often contain a variety of NATO aircraft, some even containing jets. Additionally when fast travel is enabled airfields allow players to fast travel to them, even if there is no land connection between the islands.
Airfields can be captured by killing all of the NATO garrison and then dealing with the QRF that NATO sends.